Does LazyHStack (SwiftUI) release memory for views out of screen? - ios

Question

I am trying to build a simple horizontal list of images. The images are loaded asynchronously, nothing fancy so far.
The main issue is that when scrolling and loading new images, the memory increases and never gets released. In case the images are really big, or the list of items very long, the app can crash while scrolling.
Shouldn't the LazyHStack do some memory management of views? I can not imagine this is not resolved so far, since it seems to me a very basic "feature".
The code (nothing special):
struct ThumbnailsCollectionView: View {
var imageService = ImageService.shared
#Binding var selectedIndex: Int
#State var image: UIImage?
var body: some View {
ScrollView([.horizontal]){
ScrollViewReader { reader in
LazyHStack(alignment: .bottom, spacing: 5){
ForEach((0...imageService.imageCount()-1), id: \.self) { index in
ThumbnailImageView(index: index)
}
}
}.padding(.vertical, 10)
}
}
}
struct ThumbnailImageView: View {
var imageService = ImageService.shared
var index: Int
#State var image: UIImage? = nil
var body: some View {
return Button(action: {
}) {
if let uiImage = image {
Image(uiImage: uiImage).resizable()
.aspectRatio(contentMode: .fit)
.zIndex(5)
}
else {
Rectangle().frame(width: 50, height: 50, alignment: .center)
}
}
.onAppear() {
imageService.thumbnail(at: index) { (image) in
self.image = image
}
}
}
}
ImageServiceCache
class ImageService {
static let shared = ImageService()
var thumbnailCache: NSCache<NSNumber, UIImage> = {
let cache = NSCache<NSNumber,UIImage>()
cache.countLimit = 10
return cache
}()
var urls:[URL] = {
var urls = [URL]()
for i in 0...100 {
let index = i % 4
urls.append(Bundle.main.url(forResource: "\(index)", withExtension: "jpg")!)
}
return urls
}()
func imageCount() -> Int {
return urls.count
}
func thumbnail(at index: Int, completion:#escaping (UIImage)->()) {
if let imageFromCache = thumbnailCache.object(forKey: NSNumber(integerLiteral: index)) {
return completion(imageFromCache)
}
DispatchQueue.global().async {
let image = UIImage(contentsOfFile: self.urls[index].path)!
self.thumbnailCache.setObject(image, forKey: NSNumber(integerLiteral: index))
DispatchQueue.main.async {
completion(image)
}
}
}
}